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Level measurement of Lithium Iron Phosphate with Vibrating Rod Level Switch

Lithium iron phosphate (LiFePO₄) is a type of lithium-ion battery using LiFePO, it is widely used in new energy industry. The accuracy of Lithium iron phosphate level is an important parameter to ensure safe production, which also directly affects the production continuity.

Physical properties of lithium iron phosphate

Due to its strong water absorption characteristic, lithium iron phosphate has the following physical properties:

1. Strong adsorption performance;

2. Easy to agglomerate;

3. Dielectric constant is in dynamic state and unstable.

The above properties of lithium iron phosphate make it both difficult to be measured the level and hard to select a proper level switch.

Comparison of advantages and disadvantages of various level switches

At present, the most commonly used level switches are rotary paddle switch, capacitive level switch, RF Admittance Level Switch, tuning fork level switch and vibrating rod level switch:

1. Rotary paddle switch is a kind of mechanical level switch, when the paddle is covered by measured material, the motor stops rotating and its power is switched off automatically. Due to its poor sealing, lithium iron phosphate can easily enter the gap between bearing and oil seal at the end of the shaft, then the shaft may get stuck. In addition, poor heat dissipation of the motor also leads to motor burn out problem.

2. Capacitive level switch uses two sensing electrodes, to output level signal by detecting changes in capacitance between electrodes. The capacitance value is closely related to the dielectric constant of material. However, the dielectric constant changes dynamically due to water absorption of lithium iron phosphate, which results in inaccurate measurement. Besides, the stiffness of capacitance probe (made of teflon) is weak, so the probe is easy to be bent and damaged when blocky material impacts the probe.

3. RF admittance level switch is similar to capacitive level switch in measuring principle, the changing dielectric constant is also the obstacle to accurately measure the lithium iron phosphate level.

4. Vibrating fork body of tuning fork level switch is easy to agglomerate and accumulate lithium iron phosphate material, leads to the instrument output false alarm.

5. Vibrating rod level switch uses piezoelectric ceramics to drive the probe to vibrate. When vibrating probe comes in contact with the material under measure, the vibration amplitude and the frequency of the probe will substantially decrease, so does the output of detecting piezoelectric device. Compared with rotary paddle switch, vibrating rod level switch has better sealing performance and more stable measurement due to its integrated design, and its accurate measurement is not affected by dielectric constant of materials. According to the different structure designs of the probe, vibrating rod level switch can be divided into two types: single rod structure and double rods (dual-rod) structure. For double rod vibrating rod level switch, after precise tuning, the probe is in a complete resonance state, and the probe can be driven to vibrate with a small power supply voltage, with strong anti-hanging performance and is hard to deform. However, the sensitivity and anti-hanging performance of single rod vibrating rod level switch is obviously inferior to that of double rods.

Level measurement of Lithium Iron Phosphate with Vibrating Rod Level Switch

Features of Jiwei Tube-11 Vibrating Rod Level Switch:

●　First made-in-China Vibrating Rod Level Switch that is designed with double vibrating tubes.

●　High sensitivity thanks to the fine adjustment on the resonant vibrating frequency. It is suitable for the majority of granular bulk solids. The medium density can be as low as 0.02g/cm³;

●　An industry leading product that can tolerate high process temperature up to 250℃, and ultra-high temperature up to 400℃(Water/air cooling);

●　Excellent in the medium interface detection and control;

●　Larger redundancy to avoid medium buildup and highly reliable for the medium with higher viscosity and adhesiveness;

●　Strong self-diagnostic function makes it possible to accurately locate the fault.

●　Easy installation and no calibration necessary;

●　With gas/dust Flameproof Enclosure and gas/dust Intrinsic Safety certificates & IP66/IP67 ingress protection;

●　Strong anti-corrosion probe thanks to the probe material selection, such as 316L and 318 S13.

So far, all Jiwei Tube-11 Vibrating Rod Level Switches have been running stably and effectively in the level measurement of lithium iron phosphate, which has won the trust and praise of clients. According to the feedback, the client is satisfied with the AC / DC self-adaptive and modular circuit design of Tube-11 Vibrating Rod Level Switch, the simple wiring and installation also greatly reduces the on-site maintenance cost.